class Solution {
public:
    int longestCommonSubsequence(string str1, string str2) {
        int m=str1.size(),n=str2.size();
        vector<vector<int>> dp(m+1,vector<int>(n+1));

        for(int i=1;i<=m;i++)
        {
            for(int j=1;j<=n;j++)
            {
                if(str1[i-1]==str2[j-1]) dp[i][j]=dp[i-1][j-1]+1;
                else dp[i][j]=max(dp[i-1][j],dp[i][j-1]);  
            }
        }
        return dp[m][n];
    }
};